The present invention relates to power trains, i.e., to power producing and power transmitting components of motor vehicles. More particularly, our invention relates to improvements in so-called hybrid drives which, in addition to at least one internal combustion (i.e., fuel consuming) engine, employ at least one electrical machine which is connectable with and disconnectable from the engine and can act as a generator as well as a motor, and at least one transmission or gearbox which is interposed between the engine and/or the electrical machine on the one hand, and at least one driven part (such as a differential or one or more wheels) on the other hand and can be shifted into any one of several gears in dependency upon the condition of the vehicle and/or its power train.
A characteristic of a hybrid drive is that the wheels of the motor vehicle embodying such drive can receive motion from the engine and/or from the electrical machine. Furthermore, specially designed versions of hybrid drives and of the motor vehicles embodying hybrid drives can be operated in such a way that, when the operator of the vehicle applies the brakes, kinetic energy is transmitted to the electrical machine for conversion into electrical energy which is stored in one or more batteries and/or other suitable storage facilities (e.g., one or more cells or others).
Hybrid drives of the above outlined character can compete with standard power trains only if their efficiency is very high and if they can operate satisfactorily with energy-saving engines, such as diesel engines and especially those with direct fuel injection.